Method and system for providing ultrapure water with flexible lamp configuration

ABSTRACT

A method and system of providing ultrapure water for semiconductor fabrication operations is provided. The water is treated by utilizing a free radical scavenging system. The free radical scavenging system can utilize actinic radiation with a free radical precursor compound, such as ammonium persulfate. The ultrapure water may be further treated by utilizing ion exchange media and degasification apparatus. A control system can be utilized to regulate a continuously variable intensity of the actinic radiation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application No. 62/156,487, filed May 4, 2105, titled“FLEXIBLE ELECTRICAL LAMP CONFIGURATION FOR AN ADVANCED OXIDATIONPROCESS” and to U.S. Provisional Application No. 62/160,128, filed May12, 2105, titled “VARIABLE INTENSITY LAMP FOR AN ADVANCED OXIDATIONPROCESS,” each of which being incorporated herein by reference in itsentirety for all purposes.

BACKGROUND

Aspects and embodiments disclosed herein relate to systems and methodsof providing ultrapure water and, in particular, to systems and methodsof reducing or maintaining a contaminant level of ultrapure water thatcan be used during fabrication of semiconductor devices or componentsthereof.

SUMMARY

One or more aspects relate to a system for treating water. The systemcomprises a primary actinic radiation reactor, a source of a persulfateprecursor compound disposed to introduce at least one persulfateprecursor compound into the primary actinic radiation reactor, a totalorganic carbon (TOC) concentration sensor located upstream of theprimary actinic radiation reactor, a persulfate concentration sensorlocated downstream of the primary actinic radiation reactor, and acontroller operatively coupled to receive at least one input signal fromat least one of the TOC concentration sensor and the persulfateconcentration sensor, and to generate a control signal that regulates acontinuously variable intensity of the actinic radiation in the primaryactinic radiation reactor based at least in part on the at least oneinput signal.

In some embodiments, the system further comprises a reverse osmosis unitlocated upstream of the primary actinic radiation reactor.

In some embodiments, the system further comprises a secondary actinicradiation reactor located downstream of the primary actinic radiationreactor.

In some embodiments, the system further comprises a particulate filterlocated downstream of the primary actinic radiation reactor.

In some embodiments, the system further comprises an ultrafiltrationapparatus located downstream of from the primary actinic radiationreactor.

In some embodiments, the system further comprises at least one unitoperation selected from the group consisting of a heat exchanger, adegasifier, a particulate filter, an ion purification apparatus, and anion-exchange column.

In some embodiments, the ion-exchange column is located upstream of theTOC concentration sensor.

In some embodiments, the system further comprises a source of waterlocated upstream of the primary actinic radiation reactor comprising oneor more unit operations selected from the group consisting of a reverseosmosis filter, an electrodialysis device, an electrodeionizationdevice, a distillation apparatus, an ion-exchange column, andcombinations thereof.

In some embodiments, water from the source of water comprises less thanabout 25 ppb TOC.

In some embodiments, the system further comprises a TOC concentrationsensor located downstream of the primary actinic radiation reactor.

In some embodiments, the reducing agent is sulfur dioxide.

In some embodiments, the controller is further operable to generate acontrol signal that regulates a rate at which the persulfate precursorcompound is introduced into the primary actinic radiation reactor.

In some embodiments, the primary actinic radiation reactor includes anultraviolet lamp with a double sided electrical connection.

In some embodiments, the ultraviolet lamp with the double sidedelectrical connection includes a first electrical connection to a firstelectrode on a first end of the lamp, a second electrical connection toa second electrode on the first end of the lamp, and a third electricalconnection to the second electrode on a second end of the lamp.

In some embodiments, the system further comprises a source of a reducingagent disposed to introduce at least one reducing agent downstream fromthe primary actinic radiation reactor, and a reducing agentconcentration sensor located downstream of a point of addition of the atleast one reducing agent. The controller may be further configured toreceive an input signal from the reducing agent concentration sensor andgenerate a control signal that regulates a continuously variableintensity of the actinic radiation in the primary actinic radiationreactor based at least in part on the input signal from the reducingagent concentration sensor.

In some embodiments, the controller is further operable to generate acontrol signal that regulates a rate at which the reducing agent isintroduced to the system

In accordance with another aspect, there is provided a method oftreating water. The method comprises providing a water to be treated,measuring a total organic carbon (TOC) value of the water to be treated,introducing persulfate anions to the water to be treated based in parton at least one input signal of the measured TOC value of the water tobe treated, introducing the water containing persulfate anions to aprimary reactor, exposing the persulfate anions in the water toultraviolet light in the reactor to produce an irradiated water stream,and adjusting a continuously variable intensity of the ultraviolet lightbased in part on at least one of an input signal selected from the groupconsisting of a TOC value of the water to be treated, a persulfate valueof the water downstream of the reactor, and a rate of addition ofpersulfate anions.

In some embodiments, the method further comprises exposing theirradiated water to ultraviolet light in a secondary reactor locateddownstream of the primary reactor. In some embodiments, the methodfurther comprises removing dissolved solids and dissolved gases from thewater.

In some embodiments, the method further comprises treating the water tobe treated prior to providing the water to be treated to the reactorvessel.

In some embodiments, the method further comprises introducing a reducingagent to the irradiated water.

In some embodiments, the method further comprises measuring a reducingagent concentration value of the irradiated water.

In some embodiments, the method further comprises the reducing agent tothe irradiated water based on the measured reducing agent concentrationvalue.

In some embodiments, the reducing agent is sulfur dioxide.

In some embodiments, providing the water to be treated includesproviding inlet water having a TOC value of less than about 25 ppb andtreating the water includes reducing the TOC value of the water to lessthan 1 ppb.

In accordance with another aspect, there is provided a method ofproviding ultrapure water to a semiconductor fabrication unit. Themethod comprises providing inlet water having a TOC value of less thanabout 25 ppb, introducing at least one free radical precursor compoundinto the water, converting the at least one free radical precursorcompound into at least one free radical scavenging species by exposingthe at least one free radical precursor to a UV radiation from a sourceof UV radiation having a continuously variable UV radiation poweroutput, removing at least a portion of any particulates from the waterto produce the ultrapure water, and delivering at least a portion of theultrapure water to the semiconductor fabrication unit.

In some embodiments, the method further comprises regulating a rate ofaddition of the at least one precursor compound based at least partiallyon the TOC value of the inlet water.

In some embodiments, the method further comprises regulating the UVradiation power output based at least partially on the TOC value of theinlet water.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing.

In the drawings:

FIG. 1 is a schematic drawing illustrating a system in accordance withone or more embodiments;

FIG. 2 is a schematic drawing illustrating a system in accordance withone or more embodiments;

FIG. 3 is a schematic drawing illustrating a vessel in accordance withone or more embodiments;

FIG. 4A is a schematic drawing illustrating a vessel in accordance withone or more embodiments;

FIG. 4B is a schematic drawing illustrating a vessel in accordance withone or more embodiments;

FIG. 5 is a schematic drawing illustrating a sensor and controllersystem in accordance with one or more embodiments;

FIG. 6 is a schematic drawing illustrating a processor or control systemupon which one or more embodiments may be practiced;

FIG. 7 illustrates a circuit for controlling a continuously variablypowered ultraviolet lamp in embodiments of a system in accordance withone or more embodiments;

FIG. 8 illustrates electrical parameters associated with ignition andoperation of a continuously variably powered ultraviolet lamp inembodiments of a system in accordance with one or more embodiments;

FIG. 9A illustrates an embodiment of a double sided electricalconnection lamp utilized in embodiments of a system in accordance withone or more embodiments;

FIG. 9B illustrates another embodiment of a double sided electricalconnection lamp utilized in embodiments of a system in accordance withone or more embodiments;

FIG. 9C illustrates another embodiment of a double sided electricalconnection lamp utilized in embodiments of a system in accordance withone or more embodiments; and

FIG. 9D illustrates another embodiment of a double sided electricalconnection lamp utilized in embodiments of a system in accordance withone or more embodiments.

DETAILED DESCRIPTION

One or more aspects can be directed to water treatment or purificationsystems and techniques. The various systems and techniques typicallyutilize or comprise one or more unit operations that remove undesirablespecies from a process fluid or stream. A plurality of unit operationsmay be utilized serially or in parallel flow arrangement, or acombination of serial and parallel flow arrangement, to facilitatenon-selective or selective removal or a reduction of concentration orlevel of a variety of target species or compounds, which are typicallyundesirable or objectionable, in a process stream. Further, the systemsand techniques may utilize one or more unit operations to facilitateadjustment of a concentration of a species or a byproduct speciesgenerated from a unit operation of the system. Some aspects can bedirected to techniques and systems or components thereof that treat orpurify water that, in some cases, can be characterized as having a lowlevel of impurities or contaminants. Some advantageous aspects can bedirected to systems and techniques that provide ultrapure water.Particularly advantageous aspects can be directed to systems andtechniques that provide ultrapure water for use in semiconductorprocessing or fabrication operations. Some aspects and embodimentsprovide systems and techniques that provide make-up water in acirculating water or ultrapure water system in a manner that maintains awater or ultrapure water characteristic of the water circuit containingwater or ultrapure water. The systems and techniques may, in some cases,co-mingle make-up or inlet water or ultrapure water with treated wateror ultrapure water. Still further aspects can be directed to controlsystems and techniques suitable for use with water treatment orpurification systems. Even further aspects can be directed to controlsystems and techniques that facilitate semiconductor fabricationoperations by providing ultrapure water. Indeed, some aspects may bedirected to control systems and techniques that facilitate water orultrapure water treatment or purification by utilizing a feedforward ora feedback approach or both. Even further aspects can be directed totechniques for measuring a level or concentration of a target species orcompound in the water or ultrapure water or a liquid stream. Themeasuring techniques may utilize control systems and techniques thatfacilitate providing ultrapure water.

In accordance with at least one aspect, some embodiments thereof caninvolve a system for treating water. The system and techniques caninvolve a first process train that relies on utilizing purified water tocreate conditions that are conducive to free radical scavenging alongwith one or more ancillary process trains with unit operations thatremove or at least reduce the concentration of byproducts of upstreamprocesses. The system for treating water can comprise at least one freeradical scavenging system fluidly connected to at least one source ofwater that can contain byproducts from one or more upstream processes.In certain aspects, the at least one source of water can be pure, oreven ultrapure, and preferably water having a resistivity of at least 15megohm cm. The system for treating water can also comprise, or befluidly coupled to, at least one particulate removal system that isfluidly connected downstream of the at least one free radical scavengingsystem and at least one ultrapure water delivery system that is fluidlyconnected downstream of at least one particulate removal system. Furtherthe system for treating water typically also comprises at least onewater return system that fluidly connects the at least one ultrapurewater delivery system to at least one of the free radical scavengingsystems. The free radical scavenging system, in some cases, can consistessentially of, or preferably, comprise at least one source of at leastone precursor compound. Typically, the at least one source of at leastone precursor compound is disposed or otherwise constructed and arrangedto introduce at least one free radical precursor compound into at leasta portion of the water from the at least one source of water. The freeradical scavenging system can further consist essentially of or compriseat least one source of actinic radiation with or without at least onefurther alternative apparatus that can also initiate or convert at leastone precursor compound into at least one free radical scavenging speciesin the water. In still other cases, the particulate removal system cancomprise at least one ultrafiltration apparatus. Typically, at least oneultrafiltration apparatus is fluidly connected downstream of the atleast one source of actinic radiation or at least one free radicalinitiating apparatus and, preferably, upstream of at least one ultrapurewater delivery system.

In accordance with at least one further aspect, some embodiments thereofcan involve a system for providing ultrapure water to a semiconductorfabrication unit. The system can comprise one or more sources of waterfluidly connected to at least one actinic radiation reactor. The atleast one reactor is preferably configured to irradiate water from thesource of water. The system can further comprise one or more sources ofa precursor compound. The one or more sources of precursor compound canbe disposed to introduce one or more free radical precursor compoundsinto the water from the one or more water sources.

The actinic radiation reactor may be a reactor including one or multipleultraviolet (UV) lamps that produce ultraviolet light that, whenabsorbed by the free radical precursor compound, causes free radicals tobe produced from the free radical precursor compound. The free radicalsmay oxidize dissolved organic carbon species in the water, for example,trichloromethane or urea, into less undesirable chemical species, forexample, carbon dioxide and water. Embodiments of a treatment processfor removing undesirable species, for example, organic carbon speciesfrom a fluid, for example, water, may be referred to herein an AdvancedOxidation Process (AOP) or a free radical scavenging process. Theseterms are used synonymously herein.

The system can also comprise at least one particulate filter fluidlyconnected downstream of at least one of the one or more actinicradiation reactors and, preferably, upstream of an ultrapure waterdistribution system. The ultrapure water distribution system is, in someadvantageous embodiments, fluidly connected to the semiconductorfabrication unit. The water source typically provides water having atotal organic carbon (TOC) value of less than about 25 ppb. The systemfor providing ultrapure water can further comprise a recycle line thatfluidly connects the ultrapure water distribution system, typically anoutlet port thereof, with the at least one of the source of water, theactinic radiation reactor, and the particulate filter.

In accordance with some aspects, some embodiments can involve a methodof providing ultrapure water to a semiconductor fabrication unit. Themethod can comprise one or more acts of providing inlet water having aTOC value of less than about 25 ppb, introducing at least one freeradical precursor compound into the water, and converting the at leastone free radical precursor compound into at least one free radicalscavenging species. The method can further comprise one or more acts ofremoving at least a portion of any particulates from the water toproduce the ultrapure water, and delivering at least a portion of theultrapure water to the semiconductor fabrication unit.

In accordance with other aspects, some embodiments can involve acomputer-readable medium having computer-readable signals stored thereonthat define instructions that as a result of being executed by at leastone processor, instruct the at least one processor to perform a methodof regulating addition of at least one free radical precursor compoundinto an inlet water. The inlet water, in some cases, can be pure orultrapure water, but preferably has a TOC value of less than about 25ppb. The method executable by the at least one processor can compriseone or more acts of generating one or more drive signals based at leastpartially on the TOC value of the inlet water; and transmitting the oneor more drive signals to at least one source of the at least oneprecursor compound, the at least one source disposed to introduce the atleast one precursor compound into the inlet water.

In accordance with other aspects, some embodiments can include a systemfor treating water. The system can comprise a primary actinic radiationreactor. The system can further comprise a source of a persulfateprecursor compound disposed to introduce at least one persulfateprecursor compound into the primary actinic radiation reactor. Thesystem can further comprise one or more sensors such as a total organiccarbon (TOC) concentration sensor located upstream of the primaryactinic radiation reactor. The system can further comprise a persulfateconcentration sensor located downstream of the primary actinic radiationreactor. The system can further comprise a source of a reducing agent.The reducing agent can be disposed to introduce at least one reducingagent downstream of the primary actinic radiation reactor. A reducingagent concentration sensor can also be provided. The reducing agentconcentration sensor can be located downstream of a point of addition ofthe at least one reducing agent. A controller can also be provided. Thecontroller can be operatively coupled to receive at least one inputsignal from at least one of the TOC concentration sensor, the persulfateconcentration sensor, and the reducing agent concentration sensor. Thecontroller can regulate at least one of a rate at which the persulfateprecursor compound is introduced into the primary actinic radiationreactor, an intensity of the actinic radiation in the primary actinicradiation reactor, and a rate at which the reducing agent is introducedto the system.

In accordance with yet other aspects, a method of treating water isprovided. The method can comprise providing water to be treated. Themethod can also comprise measuring a TOC value of the water to betreated, and introducing persulfate anions to the water to be treatedbased at least in part on at least one input signal of the measured TOCvalue of the water to be treated. The method can also compriseintroducing the water containing persulfate anions to a primary reactor,and exposing the persulfate anions in the water to ultraviolet light inthe reactor to produce an irradiated water stream. The method canfurther comprise adjusting an intensity of the ultraviolet light basedat least in part on at least one of an input signal selected from thegroup consisting of a TOC value of the water to be treated, a persulfatevalue of the water downstream of the reactor, and a rate of addition ofpersulfate anions. A reducing agent can be introduced to the irradiatedwater.

In accordance with yet other aspects, a method for measuring aconcentration of a compound in a liquid stream is provided. The methodcan comprise measuring a first conductivity in the liquid stream, andirradiating at least a portion of the liquid stream. The method canfurther comprise measuring a second conductivity of the liquid streamafter irradiating, and calculating the concentration of the compoundbased at least in part on the first conductivity measurement and thesecond conductivity measurement. In certain embodiments, the compoundcan be persulfate or sulfur dioxide.

In accordance with yet other aspects, a method for controllingintroduction of sulfur dioxide to a liquid stream is provided. Thesystem can comprise a persulfate concentration sensor in fluidcommunication with the liquid stream. The system can further comprise asource of sulfur dioxide. The sulfur dioxide can be disposed tointroduce sulfur dioxide to the liquid stream downstream of thepersulfate concentration sensor. The system can further comprise asulfur dioxide concentration sensor in fluid communication with theliquid stream and located downstream of the source of sulfur dioxide.The system can further comprise a controller. The controller can beconfigured to generate a control signal that regulates at least one of arate of addition of and an amount of the sulfur dioxide introduced intothe liquid stream based on at least one input signal from any one of thepersulfate concentration sensor and the sulfur dioxide stream.

In accordance with yet other aspects, an actinic radiation reactor isprovided. The actinic radiation reactor can comprise a vessel, and afirst array of tubes in the vessel. The first array of tubes cancomprise a first set of parallel tubes, and a second set of paralleltubes. Each tube can comprise at least one ultraviolet lamp and each ofthe parallel tubes of the first set is positioned to have itslongitudinal axis orthogonal relative to the longitudinal axis of thetubes of the second set.

In one or more embodiments, any of which may be relevant to one or moreaspects, the systems and techniques disclosed herein may utilize one ormore subsystems that adjusts or regulates or at least facilitatesadjusting or regulating at least one operating parameter, state, orcondition of at least one unit operation or component of the system orone or more characteristics or physical properties of a process stream.To facilitate such adjustment and regulatory features, one or moreembodiments may utilize controllers and indicative apparatus thatprovide a status, state, or condition of one or more components orprocesses. For example, at least one sensor may be utilized to provide arepresentation of an intensive property or an extensive property of, forexample, water from the source, water entering or leaving the freeradical scavenging system, water entering or leaving the particulateremoval system, or water entering or leaving an actinic radiationreactor or one or more other downstream processes. Thus, in accordancewith a particularly advantageous embodiment, the systems and techniquesmay involve one or more sensors or other indicative apparatus, such ascomposition analyzers, or conductivity cells, that provide, for example,a representation of a state, condition, characteristic, or quality ofthe water entering or leaving any of the unit operations of the system.

FIG. 1 schematically embodies a system 100 in accordance with one ormore aspects. System 100 can be representative of a water treatment orpurification system that provides water including water that can beconsidered to be ultrapure water. In some particularly advantageousembodiments, system 100 can be directed to or be representative of apurification system providing ultrapure water suitable for use insemiconductor fabrication facilities or at least maintaining anultrapure water quality. Still further aspects involve a system 100 thatcan be considered as utilizing ultrapure water to provide treatedultrapure water to one or more semiconductor fabrication units (notshown). Thus, in accordance with some aspects, system 100 can be a watertreatment system that reduces a concentration, content, or level of oneor more impurities or contaminants that may be present in make-up orinlet water from one or more water sources 110 and provide the treatedwater to a system that utilizes ultrapure water.

As exemplarily illustrated, system 100 can comprise one or more first orprimary treatment trains or systems 101 coupled to one or more second orsecondary treatment trains or systems 102. System 100 may furthercomprise at least one water distribution system 103 fluidly connected toat least one secondary treatment system and, in some even moreadvantageous configurations, to at least one primary treatment system.Further advantageous embodiments can involve configurations that involveat least one flow directional control device in at least one of theprimary treatment system, the secondary treatment system, and the waterdistribution system. Non-limiting examples of directional flow controldevices include check valves and weirs.

Preferably, source 110 provides water consisting of, consistingessentially of, or comprising a low level of impurities. Morepreferably, water from source 110 consists of, consists essentially of,or comprises ultrapure water having at least one characteristic selectedfrom the group consisting of a total organic carbon level or value ofless than about 25 ppb or even less than about 20 ppb, as urea, and aresistivity of at least about 15 megohm cm or even at least about 18megohm cm. First or primary treatment system 101 can further comprise atleast one source 122 of a precursor treating compound fluidly connectedto reactor 120.

Water introduced into system 100 from source 110 typically, or evenpreferably, can be characterized by having a low level of impurities.For example, some embodiments utilize pure or ultrapure water ormixtures thereof that have previously been treated or purified by one ormore treatment trains (not shown) such as those that utilize reverseosmosis, electrodialysis, electrodeionization, distillation, ionexchange, or combinations of such operations. As noted, advantageousembodiments involve ultrapure inlet water from source 110 that typicallyhas low conductivity or high resistivity of at least about 15 megohm cm,preferably at least about 18 megohm cm, and/or has a low level ofcontaminants as, for example, a low total organic carbon level of lessthan about 50 ppb, and preferably, less than about 25 ppb, typically asurea or other carbon compound or surrogate. In certain embodiments, theinlet water may be as low as 1 ppb. In other embodiments, the inletwater may be as low as 0.5 ppb. In yet other embodiments, theresistivity of the inlet water may be about 1 megohm cm.

In some particular embodiments, first treatment system 101 can becharacterized or comprise at least one free radical scavenging system.The free radical scavenging system 101 can comprise at least one freeradical scavenger reactor 120, such as an irradiation reactor, fluidlyconnected to at least one source 110 of water. Reactor 120 can be a plugflow reactor or a continuously stirred tank reactor, or combinationsthereof. In certain embodiments, a plug flow reactor can be used toprevent the likelihood of blinded or regions of lower irradiationintensity, such as short circuiting, of illumination by the lamps withinthe reactor. A plug flow reactor can be defined as a reactor thatoperates under conditions that facilitate laminar flow paths of fluidthrough the reactor, having parallel, non-turbulent flow paths. Reactor120 is typically sized to provide a residence time sufficient to allowfree radical species in the water flowing in the reactor to scavenge,degrade, or otherwise convert at least one of the impurities, typicallythe organic carbon-based impurities into an inert compound, one or morecompounds that may be removed from the water, or at least to one thatcan be more readily removed relative to the at least one impurity.

The reactor can additionally be sized based on the expected flow rate ofthe system to provide a sufficient or a desired residence time in thereactor. In certain embodiments, the flow rate of water through thesystem can be based on the demand for treated water downstream of thesystem, or the flow rate of water being utilized upstream of the system,or both. In certain examples, the flow rate of water through the system,or through each reactor, can be between about 1 gallon per minute (gpm)and 2000 gpm. In particular examples, the flow rate can be from about400 gpm to about 1300 gpm. In other particular examples, the flow ratecan be from about 400 gpm to about 1900 gpm. The reactor and other unitoperations and equipment of the system, such as pumps and flow valves,can be selected and sized to allow for fluctuations or changes in flowrates from about 400 gpm to about 1900 gpm.

In the free radical scavenging system, organic compounds in the watercan be oxidized by one or more free radical species into carbon dioxide,which can be removed in one or more downstream unit operations. Reactor120 can comprise at least one free radical activation device thatconverts one or more precursor compounds into one or more free radicalscavenging species. For example, reactor 120 can comprise one or morelamps, in one or more reaction chambers, to irradiate or otherwiseprovide actinic radiation to the water and divide the precursor compoundinto the one or more free radical species.

The reactor can be divided into two chambers by one or more bafflesbetween the chambers. The baffle can be used to provide mixing orturbulence to the reactor or prevent mixing or promote laminar, parallelflow paths through the interior of the reactor, such as in the chambers.In certain embodiments, a reactor inlet is in fluid communication with afirst chamber and a reactor outlet is in fluid communication with asecond chamber.

In some embodiments, at least three reactor chambers, each having atleast one ultraviolet (UV) lamp disposed to irradiate the water in therespective chambers with light of about 185 nm, 220 nm, and/or 254 nm,or ranging from about 185 nm to about 254 nm, at various power levels,are serially arranged in reactor 120. It is to be appreciated that theshorter wavelengths of 185 nm or 220 nm may be preferable in AOPprocesses because UV light at these wavelengths has sufficient photonenergy to create free radicals from free radical precursors utilized inthe process for oxidizing dissolved organic contaminants. In contrast,disinfection processes, where UV light may be utilized to kill ordisable microorganisms, may operate efficiently with UV light at the 254nm wavelength produced by low pressure lamps. Disinfection systems wouldnot typically utilize the more expensive medium pressure or highpressure UV lamps capable of providing significant UV intensity at theshorter 185 nm or 220 nm wavelengths.

Sets of serially arranged reactors can be arranged in parallel. Forexample, a first set of reactors in series may be placed in parallelwith a second set of reactors in series, with each set having threereactors, for a total of six reactors. Any one or more of the reactorsin each set may be in service at any time. In certain embodiments, allreactors may be in service, while in other embodiments, only one set ofreactors is in service.

Commercially available sources of actinic radiation systems ascomponents of free radical scavenging systems include those from, forexample, Quantrol, Naperville, Ill., as the AQUAFINE® UV system, andfrom Aquionics Incorporated, Erlanger, Ky.

As noted, aspects and embodiments disclosed herein are not limited to asingle precursor compound and may utilize a plurality of precursorcompounds. In certain embodiments, the precursor compound may be used todegrade an undesirable species. In other embodiments, the precursorcompound may be used convert an undesirable component to a removableconstituent, such as an ionized species, or a weakly charged species. Aplurality of precursor compounds may be utilized to generate a pluralityof free radical species. This complementary arrangement may beadvantageous in conditions where a first free radical scavenging speciesselectively degrades a first type of undesirable compound and a secondfree radical species selectively degrades other undesirable compounds.Alternatively, a first precursor compound may be utilized that can bereadily converted to a first converted species or a first free radicalspecies. The first free radical species can then convert a secondprecursor compound into a second converted species or a second freeradical species. This cascading set of reactions may also beadvantageous in conditions where the first free radical speciesselectively degrades or converts a first type of undesirable compoundand the second free radical species selectively degrades or convertsother undesirable compounds or in cases where conversion or activationof the second precursor compound into the second free radical speciesundesirably requires high energy levels. A plurality of compounds may beused to provide a plurality of scavenging species.

The one or more precursor compounds can be any compound that can beconverted to or facilitates conversion of a free radical scavengingspecies. Non-limiting examples include persulfate salts such as alkaliand alkali metal persulfates and ammonium persulfate or ammoniumpersulfate, hydrogen peroxide, peroxide salts such as alkali and alkalimetal peroxides, perborate salts such as alkali and alkali metalperborates, peroxydisulfate salts such as alkali and alkali metalperoxydisulfate and ammonium peroxydisulfate, acids such asperoxydisulfuric acid, peroxymonosulfuric acid or Caro's acid, andozone, as well as combinations thereof such as piranha solution. Theamount of the one or more precursor compounds can vary depending on thetype of contaminant. The precursor compound can consist of or consistessentially of ammonium persulfate which may be advantageous insemiconductor fabrication operations because it would likely providebyproducts that are not considered contaminants of such operations orbecause they can be readily removed by, for example, ion exchangesystems, in contrast to precursor compounds comprising sodium persulfatewhich can produce sodium species that are not readily removable and/orcan undesirably contaminate a semiconductor device.

In some cases, system 100 can comprise at least one degasifier 160 and,optionally, at least one particulate filter downstream of reactor 120.In some cases, system 100 can further comprise at least one apparatusthat removes at least a portion of any ionic or charged species from thewater. For example, system 100 in one or both of scavenging system 101or particulate removal system 102 can comprise a bed of ion exchangemedia or an electrically-driven ion purification apparatus, such as anelectrodialysis apparatus or an electrodeionization apparatus. Inparticularly advantageous configurations, system 100 can comprise afirst, primary or leading ion exchange column 140L comprising an ionexchange resin bed and a second, lagging or polishing ion exchangecolumn 140P, also comprising ion exchange resin bed, each seriallydisposed, relative to each other, along a flow path of the water throughsystem 100. The ion exchange columns may comprise a mixed bed of anionexchange media and cation exchange media. Other configurations, however,may be utilized. For example, lead ion exchange column 140L may compriseserially arranged layers or columns; the first layer or column canpredominantly comprise anion exchange media and the second column canpredominantly comprise cation exchange media. Likewise, although polishcolumn 140P can comprise a mixed bed of anion exchange media and cationexchange media, polish column 140P may comprise serially arranged layersof columns of a type of exchange media; the first column canpredominantly comprise anion exchange media and the second column canpredominantly comprise cation exchange media. Any of the first andsecond layers or columns may be disposed within a single vesselcomprising 140L or 140P and be practiced as layered beds of mediacontained within the columns. The ion exchange media in ion exchangecolumns 140L and 140P may be any suitable resin including those thatremove sulfate species, carbon dioxide, and ammonia or ammonium and anyother undesirable species or contaminant in the water from source 110 oras a byproduct of the free radical scavenging process. The ion exchangecolumns can be mixed bed ion exchange columns that contain anionic andcationic resin.

Commercially available media or ion exchange resins that may be utilizedinclude, but are not limited to, NR30 MEG PPQ, USF™ MEG PPQ, and USF™NANO resins from Siemens Water Technologies Corp., Warrendale, Pa., andDOWEX® resin from The Dow Chemical Company, Midland, Mich.

In some further embodiments, second treatment system 102 can comprise orbe characterized as a particulate removal system. For example, system100 can further comprise at least one particulate filter 150. Filter 150typically comprises a filtering membrane that removes or traps particlesof at least a target size. For example, filter 150 can be constructedwith filtering media or one or more membranes that trap all or at leasta majority of particles with an average diameter of at least about 10microns, in some cases, at least about 1 micron, in still other cases,at least about 0.05 micron, and even other cases, at least about 0.02micron, depending on the service requirements of the point of useconnected to the distribution system 103. Filter 150 can comprise acartridge filter with a membrane that retains particles that are greaterthan about 0.01 micron.

A particulate filter (not shown) may optionally be utilized to removeparticulates introduced with the one or more precursor compounds fromsource 122. This filter, like filter 150 may also remove particulatesgreater than 0.02 micron.

In some cases, particulate removal system 102 can comprise one or moreultrafiltration apparatus 172 and 174, each comprising a membrane thatprevents particles having an undesirable size characteristic fromflowing into the water distribution system with product water.Preferably at least two ultrafiltration apparatus are serially arrangedto facilitate removing particulates of, for example, greater than about0.1 micron, and in some cases, greater than 0.05 micron, and still othercases, greater than 0.02 micron. For example, the ultrafiltrationapparatus 172 and 174 may comprise membranes that reduce or otherwiseprovide a target or desired concentration of particulates larger than0.05 micron to a level of less than about 100 counts per liter ofproduct water to the point of use. The construction and arrangement ofthe ultrafiltration apparatus 172 and 174 may depend on the targetparticulate concentration and the size of the particulates in theultrapure water product. In some embodiments, filter 172 removes atleast a majority of the particulates of target size and filter 174serves as a polish to ensure that the concentration of particulates towater distribution system 103 is at a level that is less than or equalto the target or desired particulate concentration. In suchconfigurations, a retentate water stream from filter 172 typicallycontains a majority of the trapped particulates and can be discharged ordiscarded or used in other processes. Preferably, however, at least aportion of the retentate water stream is introduced into a particulatefilter 180 comprising a membrane or media that traps at least a portionof the particulates; the permeate stream therefrom, from which asubstantial portion of particulates is removed, can be directed to andmixed with an upstream unit operation of the system 100 such as, but notlimited to, a returning or circulating unused ultrapure product waterfrom distribution system 103, inlet water from source 110 introducedinto the free radical scavenging system 101, at least partially treatedwater from reactor 120, filter 150, degasifier 160, lead ion exchangecolumn 140L or polish ion exchange column 140P, or combinations thereof.Like filter 150, filter 180 can also be constructed to remove or reducea level of particulate material of a certain size to a particular ortarget level.

Degasifier 160 can comprise a membrane contactor or any unit operationthat reduces a concentration of any dissolved gases in the water orother gaseous byproduct of the precursor compound. Preferably, thedegasifier reduces any of the dissolved oxygen content, the dissolvednitrogen content, and the dissolved carbon dioxide content in the water.Typically, degasifier 160 utilizes a contacting membrane and a vacuumsource 162 that facilitates removal of the dissolved gases from thewater. Non-limiting examples of degasifiers that may be utilized hereinincludes those commercially available as LIQUI-CEL® membrane contactorsfrom Membrana, Charlotte, N.C.

Other ancillary unit operations may be utilized to adjust at least oneintensive or extensive property of the water provided to a point of use,which can be the semiconductor fabrication unit. For example, a heatexchanger, such as a chiller 130, may be disposed upstream of ultrapurewater distribution system 103 to reduce the temperature of at least aportion of the ultrapure water deliverable to at least one semiconductorfabrication unit. As illustrated, chiller 130 is disposed downstream ofreactor 120 but upstream of degasifier 160. Aspects and embodimentsdisclosed herein, however, are not limited to the exemplary presentedarrangement and one or more heat exchangers may be, for example, inthermal communication with the ultrapure water product downstream ofparticulate removal system 102 but upstream of water distribution system103. Indeed, a plurality of heat exchangers may be utilized. Forexample, a first heat exchanger, such as a heater, may heat the waterhaving at least one free radical precursor compound to assist ininitiating or converting the precursor compound into one or more freeradical scavenging species and a second heat exchanger, such as achiller, may cool the treated ultrapure water prior to delivery throughthe water distribution system.

Still other ancillary systems include, for example, one or more pumps166 that provide motive force for circulating the water through system100. Pump 166 may be a positive displacement pump or a centrifugal pump.Preferably, pump 166 comprises components that do not undesirablycontribute to the contamination characteristics of the product water.

Water distribution system 103 can comprise an inlet port and at leastone outlet port fluidly connected to and providing ultrapure productwater to one or more points of use (not shown), such as one or moresemiconductor fabrication units.

In some cases, for example, the water distribution system comprises amanifold 190 having an inlet port fluidly connected to free radicalscavenging system 101, particulate removal system 102, or both, and atleast one product outlet fluidly connected to at least one point of use,and at least one return outlet port fluidly connected to one or morecirculating systems 178 and 179 to recycle unused product water to oneor both of the free radical scavenging system and the particulateremoval system or into any point in system 100.

FIG. 2 schematically embodies a system 200 in accordance with one ormore aspects. System 200 can be representative of a water treatment orpurification system that provides water including water that can beconsidered to be ultrapure water. In some particularly advantageousembodiments, system 200 can be directed or be representative of apurification system providing ultrapure water suitable for semiconductorfabrication facilities or at least maintaining an ultrapure waterquality. Still further aspects involve a system 200 that can beconsidered as utilizing ultrapure water to provide treated ultrapurewater to one or more semiconductor fabrication units (not shown). In yetfurther aspects, system 200 can be directed to or be representative of apurification system providing ultrapure water suitable for processing bysystem 100 of FIG. 1 , or at least a part of a system that can provideultrapure water. Thus, in accordance with some aspects, system 200 canbe a water treatment system that reduces a concentration, content, orlevel of one or more impurities or contaminants that may be present inmake-up or inlet water from one or more water sources 210 and providethe treated water to a system that utilizes ultrapure water.

As with system 100, treatment system 200 can comprise subsystems orcomponents that converts or renders at least a portion of one or moretarget species into a species that can be removed in any one or moreseparation unit operations such as, but not limited to, degasificationsystems, particulate removal systems, and ion trapping, capturing orexchanging systems.

As exemplarily illustrated, system 200 can comprise a series of unitoperations 212, 214, and 216. Water to be treated from source of water210 can be optionally introduced to a reverse osmosis unit to removeparticulates from the water stream. Precursor compounds from source 216of precursor compounds can be introduced into filtrate 214 from reverseosmosis unit 212. The filtrate stream with the precursor compoundsdisposed therein can be introduced into free radical scavenging system218. Free radical scavenging system 218 can comprise at least one freeradical scavenger reactor or actinic radiation reactor fluidly connectedto at least one source 210 of water.

Free radical scavenging system 218 can comprise one or more reactors orvessels, each of which can be arranged serially or in parallel. Incertain embodiments, sets of serially arranged reactors can be arrangedin parallel. For example, a first set or train of reactors in series maybe placed in parallel with another set or train of reactors, also inseries, with each set having three reactors, for a total of six reactorsin free radical scavenging system 218. Any one or more of the reactorsin each set may be in service at any time. In certain embodiments, allreactors may be in service, while in other embodiments, only one set ofreactors is in service. Free radical scavenging system 218 can also beconsidered a primary actinic radiation reactor.

The reactor can be a plug flow reactor or a continuously stirred tankreactor, or combinations thereof. In certain embodiments, a plug flowreactor can be used so as to prevent or reduce the likelihood of blindedor regions of lower irradiation intensity, such as short circuiting, ofillumination by the lamps within the reactor. The reactor is typicallysized to provide a residence time sufficient to generate and/or allowfree radical species in the water flowing in the reactor to scavenge,degrade, or otherwise convert at least a portion of the at least one ofthe impurities, typically the organic carbon-based impurities into aninert or ionized compound, one or more compounds that may be removedfrom the water, or at least to one that can be more readily removedrelative to the at least one impurity. The reactor can additionally besized based on the expected flow rate of the system to provide asufficient residence time in the reactor. The reactor can also be sizedbased on the flow rate of water through the system. In certainembodiments, the flow rate of water through the system can be based onthe demand for treated water downstream of the system, or the flow ratewater being utilized upstream of the system. In certain examples, theflow rate can be between about 1 gallon per minute (gpm) and 2000 gpm.In particular examples, the flow rate can be between about 500 gpm andabout 1300 gpm. In other particular examples, the flow rate can be fromabout 1300 gpm to about 1900 gpm.

In the free radical scavenging system, organic compounds in the watercan be oxidized by one or more free radical species into carbon dioxide,which can be removed in one or more downstream unit operations. Thereactor can further comprise at least one free radical activation devicethat converts one or more precursor compounds into one or more freeradical scavenging species. For example, the reactor can comprise one ormore lamps, in one or more reaction chambers, to irradiate or otherwiseprovide actinic radiation to the water that activates, converts ordivides the one or more precursor compounds into the one or more freeradical species.

The reactor can, thus, be sized based on the number of ultraviolet lampsrequired to scavenge, degrade, or otherwise convert at least one of theimpurities, typically the organic carbon-based impurities into an inert,ionized, or otherwise removable compound, one or more compounds that maybe removed from the water, or at least to one that can be more readilyremoved relative to the at least one impurity. The number of lampsrequired can be based at least in part on lamp performancecharacteristics including the lamp intensity and spectrum wavelengths ofthe ultraviolet light emitted by the lamps. The number of lamps requiredcan be based at least in part on at least one of the expected TOCconcentration or amount in the inlet water stream and the amount ofpersulfate added to the feed stream or reactor.

Irradiated water stream 220 can exit free radical scavenging system 218and can be optionally introduced into a secondary irradiation systemwhich can also include one or more actinic radiation reactors 221.Secondary actinic radiation reactor 221 can comprise one or morevessels, each containing one or more ultraviolet lamps. As with system218, each of the vessels can be arranged serially or in parallel. Incertain embodiments, sets of serially arranged secondary reactors can bearranged in parallel. For example, two or more sets of serially arrangedsecondary reactors may be placed in parallel, with each set of seriallyarranged secondary reactors having two or more reactors. Any one or moreof the secondary reactors in each set may be in service at any time. Incertain embodiments, all secondary reactors may be in service, while inother embodiments, only one set of secondary reactors may be in service.In certain embodiments, the ultraviolet lamps may emit ultraviolet lightat a wavelength of in a range of about 185 nm to about 254 nm.

System 200 can have a source of reducing agent 224 which can introduceone or more neutralizing or reducing agents such as sulfur dioxide, tothe further irradiated water stream 222 at, for example, point ofaddition 230. The neutralizing or reducing agent can be any compound orspecies that can reduce or neutralize any of the residual precursorcompounds or derivatives thereof in irradiated water stream 222 to adesired level.

Stream 226 can be introduced to one or more downstream processes 228, orcan be used as ultrapure water in a desired application, such as in asemiconductor fabrication process.

In some advantageous embodiments, system 200 can further comprise one ormore unit operations that further remove any non-dissolved material,such as particulate filters. A particulate filter such as anultrafiltration apparatus, may be located downstream from primaryactinic radiation reactor 218.

Further advantageous embodiments can involve configurations that involveat least one flow directional control device in the system. Non-limitingexamples of directional flow control devices include check valves andweirs.

Any of sources 110 and 210 can provide water consisting of, consistingessentially of, or comprising a low level of impurities. Morepreferably, water from source 110 or 210 consists of, consistsessentially of, or comprises ultrapure water having at least onecharacteristic selected from the group consisting of a total organiccarbon level or value of less than about 25 ppb or even less than about20 ppb, as urea, and a resistivity of at least about 15 megohm cm oreven at least about 18 megohm cm. Free radical scavenging system 101 canfurther comprise at least one source 122 of a precursor compound fluidlyconnected to reactor 120.

Water introduced into system 100 and/or system 200 from source 110 andsource 210 typically, or even preferably, can be characterized as havinga low level of impurities. For example, some embodiments utilize pure orultrapure water or mixtures thereof that have previously been treated orpurified by one or more treatment trains (not shown) such as those thatutilize reverse osmosis, electrodialysis, electrodeionization,distillation, ion exchange, or combinations of such operations. Asnoted, advantageous embodiments involve ultrapure inlet water from, forexample, source 110 and/or source 210 that typically has lowconductivity or high resistivity, of at least about 15 megohm cm,preferably at least about 18 megohm cm, and/or has a low level ofcontaminants as, for example, a low total organic carbon level of lessthan about 50 ppb, and preferably, less than about 25 ppb, typically asurea or other carbon compound, or surrogate thereof.

One or more lamps can be utilized in the reactors to illuminate orirradiate the fluid contained therein. Particular embodiments caninvolve reactors having a plurality of lamps, each advantageouslydisposed or positioned therein to irradiate the fluid with one or moreillumination intensity levels for one or a plurality of illuminationperiods. Further aspects can involve utilizing the one or more lampswithin any of the reactors in configurations that accommodate orfacilitate a plurality of simultaneous illumination intensities.

The ultraviolet lamps can be advantageously positioned or distributedwithin the one or more reactors of the free radical scavenging system toirradiate or otherwise provide actinic radiation to the water asdesired. In certain embodiments, it is desired to distribute the lampswithin the one or more reactors to evenly distribute actinic radiationthroughout the reactor. In any of systems 218 and reactors 221, theultraviolet lamps of the free radical scavenging system can be adjustedto provide illumination at various intensities or various power levels.For example, ultraviolet lamps can be used that can be adjusted tooperate at a plurality of illumination modes, such as dim, rated, andboost mode, for example, a low, medium, or high mode.

In any of the systems and reactors disclosed herein, the power output ofultraviolet lamps of the free radical scavenging system may becontinuously adjusted or dimmed over a range of power levels. The poweroutput of the ultraviolet lamps may be adjustable to provide sufficientpower to remove a desired amount of TOC from fluid, e.g., water,undergoing treatment in the systems and reactors disclosed herein whilenot producing more ultraviolet radiation than is necessary. Such controlover the power output of the ultraviolet lamps decreases operating costsby reducing the power output and power consumption of the ultravioletlamps such that excess, unutilized UV radiation is not produced.

The usable lifetime of a UV lamp is related to the total power output ofthe UV lamp. For example, one type of UV lamp having a nominal powerrating of 4.9 kW exhibits a lifetime of about 4,000 hours when operatedat 4.9 kW, a lifetime of about 6,500 hours when operated at 3.5 kW, anda lifetime of about 1,000 hours when operated at 5.8 kW. Operating UVlamps at power levels that are no higher than those sufficient to removea desired amount of TOC from fluid, e.g., water, undergoing treatment inthe systems and reactors disclosed herein may thus extend the lifetimeof the UV lamps, further reducing system operating costs by reducing thefrequency of UV lamp replacement and number of UV lamps consumed overtime and associated UV lamp and labor costs.

Operating an AOP system with continuously dimmable or adjustable powerUV lamps may reduce operating costs as compared a system that modulatestotal UV power applied to a fluid undergoing treatment by selectivelyturning on or off different UV lamps for an additional reason. It isrecognized that each ON-OFF cycle for a high powered UV lamp, such asthose used in AOP systems, may reduce lamp lifetime by about 50 hours.Dimming lamps rather than turning them OFF and ON may thus increase lamplifetimes and decrease replacement costs.

The use of continuously dimmable or adjustable power UV lamps mayprovide a system with a better response time to changes in TOC than asystem that modulates total UV power applied to a fluid undergoingtreatment by selectively turning on or off different UV lamps. TypicalUV lamps used in AOP processes may require up to five minutes totransition from an OFF state to a state at which they are outputting arated amount of UV radiation. In comparison, continuously adjustable UVlamp systems as disclosed herein may be capable of substantiallyinstantaneously adjusting output UV radiation intensity. Coupled with afeedback and/or feedforward system that provides measurements of TOClevels in fluid (e.g., water) before and/or after undergoing UVirradiation at a measurement frequency of about 1 minute, 2 minutes-4minutes, or about 5 minutes to a control system operable to continuouslyadjust the power output of UV lamps of the treatment system, treatmentsystems as disclosed herein may provide substantially quicker responseto to changes in TOC levels in input liquid than prior known systems. Insystems as disclosed herein UV power intensity in treatment reactors maybe quickly adjusted in response to changes in TOC concentration of inletliquid to both avoid undesirable TOC levels in treated fluid and toreduce UV lamp power when not needed to reduce operating costs.

In some embodiments, UV lamps utilized in systems disclosed herein mayhave a nominal power rating of about 4.5 kW to about 4.9 kW and may becontinuously adjustable to operate at a power in a range of from about2.5 kW to about 5.8 kW. Different embodiments may utilize lamps havingdifferent nominal power ratings and continuously adjustable to operateover different power ranges.

One embodiment of a circuit that may be utilized to continuously controlpower provided to a UV lamp utilized in systems disclosed herein isillustrated in FIG. 7 . The electronic ballast circuit block diagram inFIG. 7 includes an AC line input voltage source (for example, 120 VAC/60Hz), an EMI (Electro Magnetic Interference) filter to blockcircuit-generated switching noise, a rectifier and smoothing capacitor,a control IC and half-bridge inverter for DC to AC conversion, and aresonant tank circuit to ignite and run the lamp. An additional circuitblock utilized for dimming is also shown; it includes a feedback circuitfor controlling the lamp current.

The lamp requires a current to preheat the filaments, a high voltage forignition, and a high-frequency AC current during running. To fulfillthese requirements, the electronic ballast circuit first performs alow-frequency AC-to-DC conversion at the input, followed by ahigh-frequency DC-to-AC conversion at the output.

The AC mains voltage is full-wave rectified and then peak-charges acapacitor to produce a smooth DC bus voltage. The DC bus voltage is thenconverted into a high-frequency, 50% duty-cycle, AC square-wave voltageusing a standard half-bridge switching circuit. The high-frequency ACsquare-wave voltage then drives the resonant tank circuit and becomesfiltered to produce a sinusoidal current and voltage at the lamp.

During pre-ignition, the resonant tank circuit is a series-LC circuitwith a high Q-factor. The Q, quality factor, of a resonant circuit is ameasure of the “goodness” or quality of a resonant circuit. A highervalue for this figure of merit corresponds to a narrower bandwidth,which is desirable in many applications. More formally, Q is the ratioof power stored to power dissipated in the circuit reactance andresistance, respectively. After ignition and during running, the tankcircuit is a series-L, parallel-RC circuit, with a Q-factor somewherebetween a high and low value, depending on the lamp dimming level.

When the UV lamp is first turned on, the control IC sweeps thehalf-bridge frequency from a maximum frequency down towards theresonance frequency of the high-Q ballast output stage. The lampfilaments are preheated as the frequency decreases and the lamp voltageand load current increase. See FIG. 8 .

The frequency keeps decreasing until the lamp voltage exceeds the lampignition voltage threshold and the lamp ignites. Once the lamp ignites,the lamp current is controlled such that the lamp runs at the desiredpower and intensity level.

To dim the UV lamp, the frequency of the half-bridge is increased,causing the gain of the resonant tank circuit to decrease and thereforelamp current to decrease. A closed-loop feedback circuit is then used tomeasure the lamp current and regulate the current to the dimmingreference level by continuously adjusting the half-bridge operatingfrequency.

The dimming can be controlled either manually or by a low controlvoltage such as 0-10 VDC. This control voltage can be generated by atotal organic carbon (TOC) monitor upstream and/or downstream of anactinic reactor including the continuously dimmable UV lamps so that theUV lamp intensity can be controlled in response to variations in eitherthe AOP feed liquid TOC or effluent TOC.

In some embodiments, different lamps in different portions of an AOPsystem or reactor may be individually controlled to operate at differentpower levels and/or to produce different intensities of UV radiation.For example, a subset of UV lamps in a reactor vessel 300 as illustratedin FIG. 3 may be operated at a first power level while a differentsubset of UV lamps may be operated at a different power level. Multiplesubsets of lamps in a reactor vessel 300 may each be operated atdifferent power levels. In systems including multiple reactors, operatedin series and/or in parallel, the different reactors may include UVlamps that are operated at different power levels and/or to producedifferent intensities of UV radiation. For example, in some embodiments,one or more intermediate TOC sensors may be disposed between one or moreupstream and one or more downstream reactors. If treatment in theupstream reactor(s) significantly reduces TOC levels in fluid (e.g.,water) undergoing treatment, and only minimal further TOC destruction isneeded in the downstream reactor(s) to produce a treated water having adesired TOC level, the power levels of the UV lamps in the upstreamand/or downstream reactors may be reduced to provide only the UVintensity necessary. In some embodiments, the power levels of the UVlamps in the upstream reactor(s) may be fixed and the power levels ofthe UV lamps in the downstream reactor(s) continuously adjustable basedon a TOC measurement of irradiated water exiting the upstreamreactor(s). Similarly, if intermediate TOC sensors indicate that the TOCin irradiated water exiting the upstream reactor(s) is undesirably orunexpectedly high, power levels of UV lamps in the downstream reactor(s)may be increased to a level appropriate to destroy a desired amount ofTOC in the irradiated water from the upstream reactor(s)

It is to be appreciated that the dimming circuit shown in FIG. 7 is forillustration purposes only. Aspects and embodiments disclosed herein arenot limited by the type of dimming ballast used or to the specificelectronic circuitry utilized.

The one or more lamps can be positioned within the one or more actinicradiation reactors by being placed within one or more sleeves or tubeswithin the reactor. The tubes can hold the lamps in place and protectthe lamps from the water within the reactor. The tubes can be made ofany material that is not substantially degraded by the actinic radiationand the water or components of the water within the reactor, whileallowing the radiation to pass through the material. The tubes can havea cross-sectional area that is circular. In certain embodiments, thetubes can be cylindrical, and the material of construction thereof canbe quartz. Each of the tubes can be the same or different shape or sizeas one or more other tubes. The tubes can be arranged within the reactorin various configurations, for example, the sleeves may extend across aportion of or the entire length or width of the reactor. The tubes canalso extend across an inner volume of the reactor.

Commercially available ultraviolet lamps and/or quartz sleeves may beobtained from Hanovia Specialty Lighting, Fairfield, N.J., EngineeredTreatment Systems, LLC (ETS), Beaver Dam, Wis., and Heraeus NoblelightGmbH of Hanau, Germany. The quartz material selected can be based atleast in part on the particular wavelength or wavelengths that will beused in the process. The quartz material may be selected to minimize theenergy requirements of the ultraviolet lamps at one or more wavelengths.The composition of the quartz can be selected to provide a desired orsuitable trasmittance of ultraviolet light to the water in the reactorand/or to maintain a desired or adequate level of transmissivity ofultraviolet light to the water. In certain embodiments, thetransmissivity can be at least about 50% for a predetermined period oftime. For example, the transmissivity can be about 80% or greater for apredetermined period of time. In certain embodiments, the transmissivitycan be in a range of about 80% to 90% for about 6 months to about oneyear. In certain embodiments, the transmissivity can be in a range ofabout 80% to 90% for up to about two years.

The tubes can be sealed at each end so as to not allow the contents ofthe reactor from entering the sleeves or tubes. The tubes can be securedwithin the reactor so that they remain in place throughout the use ofthe reactor. In certain embodiments, the tubes are secured to the wallof the reactor. The tubes can be secured to the wall through use of asuitable mechanical technique, or other conventional techniques forsecuring objects to one another. The materials used in the securing ofthe tubes is preferably inert and will not interfere with the operationof the reactor or negatively impact the purity of the water, or releasecontaminants to the water.

The lamps can be arranged within the reactor such that they are parallelto each other. The lamps can also be arranged within the reactor atvarious angles to one another. For example, in certain embodiments, thelamps can be arranged to illuminate paths or coverage regions that forman angle of approximately 90 degrees such that they are approximatelyorthogonal or perpendicular to one another. The lamps can be arranged inthis fashion, such that they form an approximately 90 degree angle on avertical axis or a horizontal axis, or any axis therebetween.

In certain embodiments, the reactor can comprise an array of tubes inthe reactor or vessel comprising a first set of parallel tubes and asecond set of parallel tubes. Each tube may comprise at least oneultraviolet lamp and each of the parallel tubes of the first set can bearranged to be at a desired angle relative to the second set of paralleltubes. The angle may be approximately 90 degrees in certain embodiments.The tubes of any one or both of the first array and the second array mayextend across an inner volume of the reactor. The tubes of the first setand the second set can be arranged at approximately the same elevationwithin the reactor.

Further configurations can involve tubes and/or lamps that are disposedto provide a uniform level of intensity at respective occupied orcoverage regions in the reactor. Further configurations can involveequispacially arranged tubes with one or more lamps therein.

The reactor may contain one or more arrays of tubes arranged within thereactor or vessel. A second array of tubes can comprise a third set ofparallel tubes, and a fourth set of parallel tubes orthogonal to thethird set of parallel tubes, each tube comprising at least oneultraviolet lamp. The fourth set of parallel tubes can also beorthogonal to at least one of the second set of parallel tubes and thefirst set of parallel tubes.

In certain embodiments, each array within the reactor or vessel can bepositioned a predetermined distance or elevation from another arraywithin the reactor. The predetermined distance between a set of twoarrays can be the same or different.

Mechanical access to the UV lamps is important since light intensity candecrease over time, rendering it desirable that lamps be replaced whentheir light output falls below an acceptable level. Chambers or reactorsthat utilize UV lamps typically have either a single sided or doublesided orientation to provide access to the electrical leads that powerthe lamps. The lamps come in either of these orientations. A singlesided lamp may have wiring routed internally back through the lamp andout the single side. Single sided chambers typically are placed whereaccess to both ends of the chamber are not available against walls orwhere access is too restricted. A double sided lamp has wires in oneside and out the other and the chamber they go into have access ports onboth sides of the chamber for placing the lamp and for the electricalleads to route through.

Manufacturing costs for nearly identical lamps with only the leadorientation changed are relative to the number of units manufactured.Therefore, if a single part can be produced that can incorporate eitherorientation it saves on price, stocking quantity, stocking space, leadtime issues, and simplify quality control.

In one embodiment, a UV lamp with double sided electrical connections isused in an AOP reactor. To utilize a double sided electrical connectionlamp in all reactor chambers, an electrical conductor to connect asource of electricity to either side of the ultraviolet lamp such as ajumper, switch, or short is located on the lamp or leads themselves toroute the power and/or ground to one or both sides. Additionally oralternatively, an electrical conductor to connect a source ofelectricity to the lamp can be located external of the lamp. Aspects andembodiments disclosed herein are not limited to the location or type ofelectrical connection on the lamp. Utilization of UV lamp with doublesided electrical connections simplifies the need for a specificorientation of the reactor chamber. Any electrical switch, jumper, orshort can be used as long as it is suitable for the required voltage andamperage. Such a lamp configuration would also allow for a tank orchamber or reactor with a double ended configuration to be placed whereaccess on only one side was available. Panel placement for powering thelamp where lead length was an issue could be resolved with thisconfiguration as well. All this leads to a more flexible apparatus forinstallation and easier servicing.

FIG. 9A illustrates one embodiment of a low pressure double sidedelectrical connection lamp 700 that may be utilized in conjunction withvarious systems disclosed herein. In some embodiments, lamp 700 is a lowpressure UV lamp rated to operate at temperatures of about 100° C. Lamp700 is illustrated as housed in a quartz sleeve 705 with a double endedconfiguration with access to the lamp 700 being provided on both ends ofthe quartz sleeve 705. Lamp 700 includes electrical contacts 710 a, 710b, and 710 c. Electrical contact 710 a is electrically coupled to anelectrode 715 a on a first side of the lamp 700. Electrical contact 710b is electrically coupled to an electrode 715 b on a second side of thelamp. Electrical contact 710 c is electrically coupled to the electrode715 b on the second side of the lamp via a conductor 720, for example, awire, passing internally through the body of the lamp 700. Power maythus be applied to the opposite electrodes 715 a, 715 b by providingpower to contacts 710 a and 710 b or to contacts 710 a and 710 c.

FIG. 9B illustrates lamp 700 mounted in sleeve 705 in a dual end entryconfiguration with electrical connection being made to lamp 700 viaelectrical conductors 725 a and 725 b making electrical contact withelectrical contacts 710 a and 710 b, respectively. FIG. 9C illustrateslamp 700 mounted in sleeve 705 in a single end entry configuration in asleeve 705 having a closed end or only one end through which access tothe lamp 700 is available. Electrical connection is made to lamp 700 inFIG. 9C via electrical conductors 725 a and 725 b making electricalcontact with electrical contacts 710 a and 710 c, respectively. Theelectrodes 715 a, 715 b and conductor 720 are omitted from FIGS. 9B and9C for clarity.

FIG. 9D illustrates an alternate embodiment of a lamp 700 mounted insleeve 705 in a single end entry configuration. In this embodiment,electrical contact is made via electrical conductor 725 a to electricalcontact 710 a on a first side of the lamp 700. Electrical contact ismade via electrical conductor 725 b to electrical contact 710 b by aconductor 730, for example, a wire or rail disposed external to the bodyof the lamp 700 within the sleeve 705. The embodiment of FIG. 9D may beappropriate for medium pressure UV lamps operating at temperatures ofabout 700° C. to about 900° C. where an internal conductor asillustrated in FIG. 9A might not provide a desired level of reliability.

FIG. 3 exemplarily shows a cross-sectional view of a reactor vessel 300that can be used in system 100 or system 200 or both. Reactor vessel 300typically comprises inlet 310, outlet 320, and baffle 315 which dividesreactor vessel 300 into upper chamber 325 and lower chamber 330. Reactorvessel 300 can also comprise manifold 305 which can be configured todistribute water introduced through inlet 310 throughout the vessel. Incertain embodiments, manifold 305 can be configured to evenly distributewater throughout the vessel. For example, manifold 305 can be configuredto evenly distribute water throughout the vessel such that the reactoroperates as a plug flow reactor.

In some embodiments, the reactor vessel may comprise more than onebaffle 315 to divide the reactor vessel into more than two chambers.Baffle 315 can be used to provide mixing or turbulence to the reactor.In certain embodiments, as shown in FIG. 3 , reactor inlet 310 is influid communication with lower chamber 330 and reactor outlet 320 is influid communication with upper chamber 325.

In some embodiments, at least three reactor chambers, each having atleast one ultraviolet (UV) lamp disposed to irradiate the water in therespective chambers with light of about or ranging from about 185 nm toabout 254 nm, 220 nm, and/or 254 nm at a desired or at various powerlevels, are serially arranged in reactor 120.

The reactor vessel can also comprise a plurality of ultraviolet lampspositioned within tubes, for example tubes 335 a-c and 340 a-c. In oneembodiment, as shown in FIG. 3 , reactor vessel 300 comprises a firstset of parallel tubes, tubes 335 a-c and a second set of parallel tubes(not shown). Each set of parallel tubes of the first set isapproximately orthogonal to the second set to form first array 345.Tubes 335 a-c and the second set of parallel tubes are at approximatelythe same elevation in reactor vessel 300, relative to one another.

Further, the reactor vessel can comprise a third set of parallel tubesand a fourth set of parallel tubes. Each set of parallel tubes of thefirst set is approximately orthogonal to the second set to form, forexample, second array 350. As exemplarily illustrated, tubes 340 a-c andthe second set of parallel tubes are at approximately the same elevationin reactor vessel 300, relative to one another. As shown in FIG. 3 ,first array 345 can be positioned at a predetermined distance fromsecond array 350. Vessel 300 can additionally comprise third array 355and fourth array 360, each optionally having similar configurations asfirst array 340 and second array 345.

In another embodiment, a first tube 335 b can be arranged orthogonal toa second tube 340 b to form a first array. Additionally, a set of tubes,tube 365 a and tube 365 b can be arranged orthogonal to another set oftubes, tube 370 a and tube 370 b to form a second array. The position ofthe lamps of the second array are shown in FIG. 4A, including lamps 414,420, 422, and 424. The positions of the lamps in the first array and thesecond array are shown in FIG. 4B, including lamps 426 and 428 of thefirst array and lamps 414, 420, 422, and 424 of the second array.

The lamps can generate a pattern, depending on various properties of thelamp, including the dimensions, intensity, and power delivered to thelamp. The light pattern generated by the lamp is the general volume ofspace to which that the lamp emits light. In certain embodiments thelight pattern or illumination volume is defined as the area or volume ofspace that the lamp can irradiate or otherwise provide actinic radiationto and allow for division or conversion of the precursor compound intothe one or more free radical species.

As shown in FIGS. 4A and 4B, which shows exemplarily cross-sectionalviews of reactor 400 in which a first set of tubes 410 a-c are arrangedparallel to one another, and a second set of tubes 412 a-c are arrangedparallel to one another. As shown, first set of tubes 410 a-c isarranged orthogonal relative to second set of tubes 412 a-c. Lamps, suchas lamps 414, are dispersed within tubes 410 a-c and 412 a-c, and whenilluminated, can generate light pattern 416.

One or more ultraviolet lamps, or a set of lamps, can be characterizedas projecting actinic radiation parallel an illumination vector. Theillumination vector can be defined as a direction in which one or morelamps emits actinic radiation. In an exemplarily embodiment, as shown inFIG. 4A, a first set of lamps, including lamp 420 and 422, is disposedto project actinic radiation parallel to illumination vector 418.

A first set of ultraviolet lamps each of which is disposed to projectactinic radiation parallel a first illumination vector can be energized.A second set of ultraviolet lamps each of which is disposed to projectactinic radiation parallel a second illumination vector can also beenergized. At least one of the direction of the illumination and theintensity of at least one of the first set of ultraviolet lamps andsecond set of ultraviolet lamps can be adjusted. Each set of ultravioletlamps can comprise one or more ultraviolet lamps.

The number of lamps utilized or energized and the configuration of thelamps in use can be selected based on the particular operatingconditions or requirements of the system. For example, the number oflamps utilized for a particular process can be selected and controlledbased on characteristics or measured or calculated parameters of thesystem. For example measured parameters of the inlet water or treatedwater can include any one or more of TOC concentration, temperature, andflow rate. The number of energized lamps can also be selected andcontrolled based on the concentration or amount of persulfate added tothe system. For example, 12 lamps in a particular configuration can beused if the flow rate of the water to be treated is at or below acertain threshold value, for example a nominal or design flow rate, suchas 1300 gpm, while more lamps can be used if the flow rate of the waterto be treated rises above the threshold value. For example, if the flowrate increases from 1300 gpm to a selected higher threshold value,additional lamps can be energized. For example, 24 lamps may be used ifthe flow rate of the water to be treated reaches 1900 gpm. Thus the flowrate of the water can be partially determinative of which lamps and/orthe number of energized lamps in each reactor.

In certain embodiments, the ultraviolet lamps can be operated at one ormore illumination intensity levels. For example, one or more lamps canbe used that can be adjusted to operate at a plurality of illuminationmodes, such as at any of dim, rated, and boost mode, for example, a low,medium, or high mode. The illumination intensity of one or more lampscan be adjusted and controlled based on characteristics or measured orcalculated parameters of the system, such as measured parameters of theinlet water or treated water, including TOC concentration, temperature,and flow rate. The illumination intensity of one or more lamps can alsobe adjusted and controlled based on the concentration or amount ofpersulfate added to the system. For example, the one or more lamps canbe used in a dim mode up to a predetermined threshold value of ameasured parameter of the system, such as a first TOC concentration. Theone or more lamps can be adjusted to rated mode if the measured orcalculated TOC concentration reaches or is above a second TOCconcentration, which may be above the threshold value. The one or morelamps can further be adjusted to a boost mode if the measured orcalculated TOC concentration reaches or is above a second thresholdvalue.

The lamps and the illumination intensity threreof can be controlledtogether or separately, using the same or different measured parametersand values as thresholds for adjustment.

In some embodiments, the reactor can operate in a first mode which isindicative of a first lamp configuration and a first lamp intensity. Thereactor can operate at the first mode for a particular range or up to aselected or desired value of one or more parameters of the system. Forexample, the reactor can operate at the first mode for a particularrange or up to a selected or desired value, such as a first thresholdvalue, of one or more of the TOC concentration, amount and/or rate ofaddition of persulfate, and flowrate of the inlet water or the flowrateof the water going through the reactor. At or above the selected ordesired value of one or more of the parameters, or a first thresholdvalue, the reactor can operate in a second mode which is indicative ofat least one of a second lamp configuration and a second lamp intensity.The reactor can operate in the second mode for a particular range or upto a selected or desired value, such as a second threshold value, of oneor more parameter of the system. At or above the second threshold value,the reactor can operate in a third mode which is indicative of at leastone or a third lamp configuration and a third lamp intensity.

The system can also be designed such that the reactor can be operated toallow adjustment from the third mode to the second mode, or the secondmode to the first mode based on one or more selected or desiredthreshold values. The system can be operated such that one or morethreshold levels are selected or inputed into the system, and the systemcan be operated in one or more operating modes.

In some particular embodiments, for example, the first mode may beindicative of the system operating at less than 30% of the designed flowrate capacity of the system, or less than 30% of the TOC concentrationof the target TOC concentration of the inlet water, or less than 30% ofthe maximum amount or rate of addition of persulfate that can be addedto the reactor. The second mode may be indicative of the systemoperating at 30% to 100% of the designed flow rate capacity of thesystem, or 30% to 100% of the TOC concentration of the target TOCconcentration of the inlet water, or 30% to 100% of the maximum amountor rate of addition of persulfate that can be added to the reactor. Thethird mode may be indicative of the system operating at greater than100% of the designed flow rate capacity of the system, or greater than100% of the TOC concentration of the target TOC concentration of theinlet water, or greater than 100% of the maximum amount or rate ofaddition of persulfate that can be added to the reactor.

TOC measurements can be made at one or more points along the flow pathof the water through the system, for example, system 100 or system 200.TOC measurements can be performed prior to addition of a precursorcompound to the actinic radiation reactor or to the water stream. Incertain embodiments TOC measurements are made on a water sample that hasbeen processed through a mixed bed ion exchange column so as to removeionic compounds from the water sample that may interfere with the TOCmeasurement. The mixed bed ion exchange column can comprise anionic andcationic resins that allow the transfer of ionic species from the wateronto the resin, thereby removing at least a portion of these speciesfrom the water. By removing the ionic species from the water, the TOCmeasurement can be performed more accurately. In particular examples,the mixed bed ion exchange column may be located downstream from areverse osmosis unit, and upstream of the actinic radiation reactor. Themixed bed ion exchange column may utilize USF™ NANO resin from EvoquaWater Technologies LLC., Warrendale, Pa.

TOC measurements can also be made downstream of primary actinicradiation reactor 218 or downstream of secondary actinic radiationreactor 221.

In some aspects, measurement of a compound in the water to be treated orbeing treated can be performed. This can involve measuring acharacteristic of the water. The measurement can also involve convertinga first species in the water to a target species, or changing acharacteristic of the water, and re-measuring the characteristic of thewater. In certain examples, the target species can be sulfate ions. Themeasurement of the compound can be performed down to levels, forexample, of less than 1 ppm. In some examples, the measurement of thecompound can be performed down to levels of, for example, less than 100ppb, 1 ppb, or 0.5 ppb.

In certain embodiments, the measurement of a compound in the water caninvolve measuring a first conductivity of the water or liquid stream,irradiating at least a portion of the water or liquid stream, measuringa second conductivity of the water or liquid stream after irradiating,and calculating a concentration of the compound based at least in parton the first conductivity measurement and the second conductivitymeasurement. The compound that is measured can be persulfate.Irradiating the water or liquid stream can comprise converting at leasta portion of the compound comprising persulfate into sulfate ions. Thecompound that is measured can also be a reducing agent such as sulfurdioxide. Irradiating the water or liquid stream can comprise convertingat least a portion of the compound comprising sulfur dioxide to sulfateions. The measurement of the compound in the water can be performed onthe water stream being treated, for example, in system 100 or system200, or can be performed on a side stream of the water being treated insystem 100 or system 200.

As shown in FIG. 2 , using sensor 207, a measurement of the amount of acompound in the water or liquid stream can be provided by, for example,concentration or conductivity measurements. In some embodiments, a firstconductivity of the water stream output of vessel 220 can be measured.This water stream can be irradiated by ultraviolet light, and a secondconductivity of the water stream can be measured. By comparing the firstconductivity measurement to the second conductivity measurement, aconcentration or amount of persulfate in the water stream can bedetermined. In some embodiments, a catalyst may be used instead ofutilizing ultraviolet light.

Similarly, using sensor 208, a measurement of the amount of reducingagent in the water or liquid stream can be provided. A firstconductivity of the water stream downstream from point of addition 230of reducing agent from the source of reducing agent 224 can be measuredusing sensor 208. This water stream can be irradiated by ultravioletlight, and then a second conductivity of the water stream can bemeasured. By comparing the first conductivity measurement to the secondconductivity measurement, a concentration or amount of reducing agent inthe water stream can be determined. In some embodiments, a catalyst maybe used instead of utilizing ultraviolet light.

One embodiment utilizing sensor 207 and sensor 208 is shown in FIG. 5 .A water stream 520 which may be an output from a primary actinicradiation reactor or a secondary radiation reactor may be measured withsensor 507. Sensor 507 can measure a first conductivity of water stream520. This water stream can then be irradiated by ultraviolet light, anda second conductivity of water stream 520 can be measured. Usingcontroller 532, a concentration or amount of persulfate in the waterstream can be determined by comparing the first conductivity measurementto the second conductivity measurement.

Similarly, using sensor 508, a measurement of the amount of reducingagent, such as sulfur dioxide, in water or liquid stream 526 can beprovided. A first conductivity of water stream 526, which is downstreamfrom point of addition 530 of reducing agent can be measured usingsensor 508. The sensor can irradiate water stream 526 with ultravioletlight, and then a second conductivity of water stream 526 can bemeasured. Using controller 532, a concentration or amount of reducingagent in the water stream can be determined by comparing the firstconductivity measurement to the second conductivity measurement.

At least one of the calculated concentration or amount of persulfate andthe calculated concentration or amount of reducing agent in water stream520 and water stream 526 can be utilized by controller 532 to controlthe rate or amount of reducing agent added to water stream 522. Incertain embodiments, the rate or amount of reducing agent is controlledto provide a minimum amount of reducing agent based on the calculatedconcentration of persulfate measured using sensor 507. The rate oramount of reducing agent can also be controlled to provide a minimumamount of reducing agent based on the calculated concentration ofreducing agent measured using sensor 508.

In certain embodiments, the persulfate (S₂O₈) concentration, for examplein stream 222 or 522, can be calculated based on the following formula:S₂O₈(ppb)=[conductivity cell 2 (μS)−conductivity cell 1 (μS)]×γ,wherein γ is a constant determined based on, for example, theconductivity of sulfate and the conductivity of persulfate.

Although FIG. 5 is illustrated with each of sensor 507 and sensor 508comprising two conductivity cells, it can be envisioned that each ofsensor 507 and sensor 508 can comprise one conductivity cell in which afirst conductivity of a water sample is measured, irradiation of thewater sample occurs, and a second conductivity of the water sample ismeasured. The above equation can be used to determine the persulfateconcentration, wherein ‘conductivity cell 2’ represents the secondmeasured conductivity of the water, and ‘conductivity cell 1’ representsthe first measured conductivity of the water.

In certain embodiments, it is desired to reduce or neutralize residualpersulfate in the irradiated water that exits the actinic radiationreactor to a target level. This may be achieved by including additionalultraviolet lamps or actinic radiation lamps downstream from the primaryactinic radiation reactor, which can help reduce the residual persulfateand reduce TOC. For example, FIG. 2 includes secondary actinic radiationreactor 220 which can be added to help reduce the residual persulfateand reduce the TOC in the water.

Techniques such as utilizing catalysts or reducing agents can be used toreduce or neutralize the residual persulfate in the water stream.Reducing agents may include bisulfites and sulfur dioxide. The reducingagent can be added to the water stream based on the persulfate andreducing agent measurements, or other characteristics or properties ofthe system. The rate of addition can be adjusted during the process asthe needs of the system changes.

Systems 100 and 200 can further comprise one or more control systems orcontrollers 105 and 232. Control systems 105 and 232 are typicallyconnected to one or more sensors or input devices configured anddisposed to provide an indication or representation of at least oneproperty, characteristic, state or condition of at least one of aprocess stream, a component, or a subsystem of treatment systems 100 and200. For example, control system 105 can be operatively coupled toreceive input signals from any one or more of source 110 and sensors106, 107, and 108. Control system 232 can be operatively coupled toreceive input signals from any one or more of source 210 and sensors206, 207, 208, and 209. The input signals can be representative of anyintensive property or any extensive property of the water from source110, or water stream in the system. For example, input signals can berepresentative of any intensive property or any extensive property ofthe treated ultrapure water from ion exchange column 140L, and ionexchange column 140P of FIG. 1 . The input signals can also berepresentative of any intensive property or any extensive property ofthe treated ultrapure water from reverse osmosis unit 212, secondaryactinic radiation reactor 220, or after point of addition of reducingagent 230. For example, one or more input signals from source 110 orsource 210 can provide an indication of the resistivity or conductivity,the flow rate, the TOC value, the temperature, the pressure, theconcentration of metals, the level or amount of bacteria, the dissolvedoxygen content, and/or the dissolved nitrogen content of the inlet ormake-up water. Input devices or sensors 106, 107 and 108, and 206, 207,208, and 209 may likewise provide any one or more such representationsof the at least partially treated water through system 100 or system200. In particular, any one of the sensors can provide an indication ofthe temperature, conductivity, or concentration of a particular compoundor species in the at least partially treated water or ultrapure water.Although only sensors 106, 107, and 108 and 206, 207, 208, and 209 areparticularly depicted, additional sensors may be utilized including, forexample, one or more temperature, conductivity or resistivity sensors insystems 100 and 200.

Control systems 105 and 232 can be configured to receive any one or moreinput signals and generate one or more drive, output, and controlsignals to any one or more unit operations or subsystems of treatmentsystems 100 and 200. As illustrated, control systems 105 and 232 can,for example, receive an indication of a flow rate, a TOC level, or both,of water from source 110 and/or 210, or from another position within thesystem. Control systems 105 and 232 can then generate and transmit adrive signal to source 122 or source 216 of precursor compound to, ifnecessary, adjust the rate of addition of the precursor compoundintroduced into the water stream entering reactor 120 or reactor 218. Inone embodiment, control system 232 can, for example, receive anindication of a concentration of a particular compound or species in thewater from sensor 207 and sensor 208. Control system 232 can thengenerate and transmit a drive signal to source 224 of reducing agent to,if necessary, adjust the rate of addition of the reducing agentintroduced into the water stream at point of addition 230. The drivesignal is typically based on the one or more input signals and a targetor predetermined value or set-point. For example, if the input signalthat provides a representation of the TOC value of the inlet water fromsource 110 or source 210 is above the target TOC value or a range ofacceptable TOC value, i.e., a tolerance range, then the drive signal canbe generated to increase an amount or a rate of addition of theprecursor compound from source 122 or source 216. The particular targetvalues are typically field-selected and may vary from installation toinstallation and be dependent on downstream, point of use requirements.This configuration inventively avoids providing water having undesirablecharacteristics by proactively addressing removal of contaminants andalso avoids compensating for the system's residence or lag responsetime, which can be a result of water flowing through the system and/orthe time required for analysis.

In some embodiments, control systems 105 and 232 can, for example,receive an indication of a flow rate, a TOC concentration or level,and/or a persulfate amount or rate of addition, and generate andtransmit a drive signal to reactor 120 or reactor 218 or 220, or morespecifically to the lamps of the reactor to adjust or modify at leastone of the one or more lamps in operation and the intensity of thelamps. The drive signal can be based on the one or more input signalsand a target or predetermined value or set-point, or threshold value.For example, if the input signal that provides a representation of theTOC value of the inlet water from source 110 or source 210 is above thetarget TOC value or threshold value, or a range of acceptable TOC value,i.e., a tolerance range, then the drive signal can be generated toadjust the operating mode of the reactor by adjusting at least one ofthe lamp configuration and the lamp intensity.

Control systems 105 and 232 may further generate and transmit additionalcontrol signals to, for example, energize or adjust an intensity orpower of output radiation emitted by at least one radiation source inreactor 120, 218, or 220. Thus, depending on the amount or rate ofaddition of the precursor compound, or on the level of TOC in the waterstream entering the reactors, the control signal may be increased ordecreased appropriately, incrementally or proportionally. This featureserves to prolong service life of the one or more radiation sources andreduce energy consumption.

Control systems 105 and 232 may also be configured in feedbackarrangement and generate and transmit one or more control signals to anyone or both of the precursor compound source 122 and 214, and reactors120, 218, and 220, and reducing agent source 224. For example, the TOCvalue or the resistivity, or both, of the ultrapure product water indistribution system 103, or from the sensors 107 or 108, may be utilizedto generate control signals to any of source 122 and reactor 120.

During periods of high initial TOC fluctuations, the feedforward controlcan be utilized to compensate for instrument delay. This preemptiveapproach injects the precursor compound, typically at a surplus relativeto the amount of contaminants. During periods of stable TOC levels, thefeedback approach may be utilized with or without the feedforwardcontrol.

Control system 105 may further generate and transmit a control signalthat adjusts a rate of heat transfer in chiller 130 based on, forexample, an input signal from sensors 107 or 108, or both. The controlsignal may increase or decrease the flow rate and/or the temperature ofthe cooling water introduced into chiller 130 to provide treated waterto distribution system 103 at a desired or predetermined temperature.

Control system 105 may further generate and transmit a control signalthat energizes pump 166 or adjust a flow rate of the at least partiallytreated water flowing therethrough. If the pump utilizes a variablefrequency drive, the control signal can be generated to appropriatelyadjust the pump motor activity level to achieve a target flow ratevalue. Alternatively, an actuation signal may actuate a valve thatregulates a rate of flow of the at least partially treated water frompump 166.

Control systems 105 and 232 may be implemented using one or moreprocessors as schematically represented in FIG. 6 . Control system 105may be, for example, a general-purpose computer such as those based onan Intel PENTIUM®-type processor, a Motorola PowerPC® processor, a SunUltraSPARC® processor, a Hewlett-Packard PA-RISC® processor, or anyother type of processor or combinations thereof. Alternatively, thecontrol system may include specially-programmed, special-purposehardware, for example, an application-specific integrated circuit (ASIC)or controllers intended for analytical systems.

Control systems 105 and 232 can include one or more processors 605typically connected to one or more memory devices 650, which cancomprise, for example, any one or more of a disk drive memory, a flashmemory device, a RAM memory device, or other device for storing data.Memory device 650 is typically used for storing programs and data duringoperation of the systems 100 and 200 and/or control systems 105 and 232.For example, memory device 650 may be used for storing historical datarelating to the parameters over a period of time, as well as operatingdata. Software, including programming code that implements embodiments,can be stored on a computer readable and/or writeable nonvolatilerecording medium, and then typically copied into memory device 650wherein it can then be executed by processor 605. Such programming codemay be written in any of a plurality of programming languages, forexample, Java, Visual Basic, C, C#, or C++, Fortran, Pascal, Eiffel,Basic, COBAL, or any of a variety of combinations thereof.

Components of control system 105 and 232 may be coupled by aninterconnection mechanism 610, which may include one or more busses,e.g., between components that are integrated within a same device,and/or a network, e.g., between components that reside on separatediscrete devices. The interconnection mechanism typically enablescommunications, e.g., data, instructions, to be exchanged betweencomponents of the system.

Control systems 105 and 232 can also include one or more input devices620 receiving one or more input signals i₁, i₂, i₃, . . . , i_(n), from,for example, a keyboard, mouse, trackball, microphone, touch screen, andone or more output devices 630, generating and transmitting, one or moreoutput, drive or control signals, s₁, s₂, s₃, . . . , s_(n), to forexample, a printing device, display screen, or speaker. In addition,control systems 105 and 232 may contain one or more interfaces 660 thatcan connect control systems 105 or 232 to a communication network (notshown) in addition or as an alternative to the network that may beformed by one or more of the components of the system.

According to one or more embodiments, the one or more input devices 620may include components, such as but not limited to, valves, pumps, andsensors 106, 107, and 108, and 206, 207, 208, and 209 that typicallyprovide a measure, indication, or representation of one or moreconditions, parameters, or characteristics of one or more components orprocess streams of systems 100 and 200. Alternatively, the sensors, themetering valves and/or pumps, or all of these components may beconnected to a communication network that is operatively coupled tocontrol systems 105 and 232. For example, sensors 106, 107, and 108 and206, 207, 208, and 209 may be configured as input devices that aredirectly connected to control systems 105 and 232, metering valvesand/or pumps of subsystems 122 and 124 may be configured as outputdevices that are connected to control system 105, and any one or more ofthe above may be coupled to a computer system or an automated system, soas to communicate with control systems 105 and 232 over a communicationnetwork. Such a configuration permits one sensor to be located at asignificant distance from another sensor or allow any sensor to belocated at a significant distance from any subsystem and/or thecontroller, while still providing data therebetween.

Control systems 105 and 232 can comprise one or more storage media suchas a computer-readable and/or writeable nonvolatile recording medium inwhich signals can be stored that define a program or portions thereof tobe executed by, for example, one or more processors 605. The one or morestorage media may, for example, be or comprise a disk drive or flashmemory. In typical operation, processor 605 can cause data, such as codethat implements one or more embodiments, to be read from the one or morestorage media into, for example, memory device 640 that allows forfaster access to the information by the one or more processors than doesthe one or more media. Memory device 640 is typically a volatile, randomaccess memory such as a dynamic random access memory (DRAM) or staticmemory (SRAM) or other suitable devices that facilitates informationtransfer to and from processor 605.

Although control systems 105 and 232 is shown by way of example as onetype of computer system upon which various aspects may be practiced, itshould be appreciated that aspects and embodiments disclosed herein arenot limited to being implemented in software, or on the computer systemas exemplarily shown. Indeed, rather than being implemented on, forexample, a general purpose computer system, the control system, orcomponents or subsystems thereof, may be implemented as a dedicatedsystem or as a dedicated programmable logic controller (PLC) or in adistributed control system. Further, it should be appreciated that oneor more features or aspects may be implemented in software, hardware orfirmware, or any combination thereof. For example, one or more segmentsof an algorithm executable by processor 605 can be performed in separatecomputers, each of which can be in communication through one or morenetworks.

System 100 can further comprise a subsystem 176 for sanitizing and/orremoving any residue, particulate or other material retained on thesurface of the membranes of filtration apparatus 172 and 174. Subsystem176 can comprise one or more heat exchangers and pumps that allowtemperature cycling of the membranes of apparatus 172 and 174.Temperature cycling can be controlled by control system 105 byalternately providing hot and cool water into any of apparatus 172 and174 to allow expansion and contraction of components thereof whichfacilitates removal of any retained materials. Although not illustrated,subsystem 176 may also be connected to any unit operation of system 100to also facilitate cleaning and hot water sanitization of such unitoperations.

Having now described some illustrative embodiments, it should beapparent to those skilled in the art that the foregoing is merelyillustrative and not limiting, having been presented by way of exampleonly. Numerous modifications and other embodiments are within the scopeof one of ordinary skill in the art and are contemplated as fallingwithin the scope. In particular, although many of the examples presentedherein involve specific combinations of method acts or system elements,it should be understood that those acts and those elements may becombined in other ways to accomplish the same objectives.

Those skilled in the art should appreciate that the parameters andconfigurations described herein are exemplary and that actual parametersand/or configurations will depend on the specific application in whichthe systems and techniques are used. Those skilled in the art shouldalso recognize or be able to ascertain, using no more than routineexperimentation, equivalents to the specific embodiments. It istherefore to be understood that the embodiments described herein arepresented by way of example only and that, within the scope of theappended claims and equivalents thereto; the aspects and embodimentsdisclosed herein may be practiced otherwise than as specificallydescribed.

Moreover, it should also be appreciated that the aspects and embodimentsdisclosed herein are directed to each feature, system, subsystem, ortechnique described herein and any combination of two or more features,systems, subsystems, or techniques described herein and any combinationof two or more features, systems, subsystems, and/or methods, if suchfeatures, systems, subsystems, and techniques are not mutuallyinconsistent, is considered to be within the scope as embodied in theclaims. Further, acts, elements, and features discussed only inconnection with one embodiment are not intended to be excluded from asimilar role in other embodiments.

As used herein, the term “plurality” refers to two or more items orcomponents. The terms “comprising,” “including,” “carrying,” “having,”“containing,” and “involving,” whether in the written description or theclaims and the like, are open-ended terms, i.e., to mean “including butnot limited to.” Thus, the use of such terms is meant to encompass theitems listed thereafter, and equivalents thereof, as well as additionalitems. Only the transitional phrases “consisting of” and “consistingessentially of,” are closed or semi-closed transitional phrases,respectively, with respect to the claims. Use of ordinal terms such as“first,” “second,” “third,” and the like in the claims to modify a claimelement does not by itself connote any priority, precedence, or order ofone claim element over another or the temporal order in which acts of amethod are performed, but are used merely as labels to distinguish oneclaim element having a certain name from another element having a samename (but for use of the ordinal term) to distinguish the claimelements.

What is claimed is:
 1. A method of treating water comprising: Providingwater to be treated; Measuring a total organic carbon (TOC) value of thewater to be treated; Introducing persulfate anions to the water to betreated based in part on at least one input signal of the measured TOCvalue of the water to be treated; Introducing the water containingpersulfate anions to a primary reactor; Exposing the persulfate anionsin the water to ultraviolet light in the reactor to produce anirradiated water stream; Providing an electronic ballast circuitincluding a resonant tank circuit having a power output operativelycoupled to the ultraviolet light, the electronic ballast circuitoperable to control the continuously variable intensity of theultraviolet light over a continuous range of power levels bycontinuously measuring the current supplied to the ultraviolet light andadjusting a frequency of a drive voltage supplied to the resonant tankcircuit responsive to at least one input signal from the measured TOCvalue; Wherein the electronic ballast circuit controls the continuouslyvariable intensity of the ultraviolet light to provide sufficient powerto the ultraviolet light to remove a desired amount of TOC from fluidundergoing treatment while not producing more ultraviolet radiation thanis necessary to remove the desired amount of TOC; and Adjusting thecontinuously variable intensity of the ultraviolet light based in parton at least one of an input signal selected from the group consisting ofa TOC value of the water to be treated, a persulfate value of the waterdownstream of the reactor, and a rate of addition of persulfate anions.2. The method of claim 1, further comprising exposing the irradiatedwater to ultraviolet light in a secondary reactor located downstream ofthe primary reactor.
 3. The method of claim 1, further comprisingremoving dissolved solids and dissolved gases from the water.
 4. Themethod of claim 1, further comprising treating the water to be treatedprior to providing the water to be treated to the reactor vessel.
 5. Themethod of claim 1, further comprising introducing a reducing agent tothe irradiated water.
 6. The method of claim 5, further comprisingmeasuring a reducing agent concentration value of the irradiated water.7. The method of claim 6, further comprising introducing the reducingagent to the irradiated water based on the measured reducing agentconcentration value.
 8. The method of claim 5, wherein the reducingagent is sulfur dioxide.
 9. The method of claim 1, wherein providing thewater to be treated includes providing inlet water having a TOC value ofless than about 25 ppb and treating the water includes reducing the TOCvalue of the water to less than 1 ppb.
 10. A method of providingultrapure water to a semiconductor fabrication unit, comprising:Providing inlet water having a TOC value of less than about 25 ppb;Introducing at least one free radical precursor compound into the water;Converting the at least one free radical precursor compound into atleast one free radical scavenging species by exposing the at least onefree radical precursor to UV radiation from a source of UV radiationhaving a continuously variable UV radiation power output; Providing anelectronic ballast circuit including a resonant tank circuit having apower output operatively coupled to the source of UV radiation, theelectronic ballast circuit operable to control the continuously variableintensity of the source of UV radiation over a continuous range of powerlevels by continuously measuring the current supplied to the source ofUV radiation and adjusting a frequency of a drive voltage supplied tothe resonant tank circuit responsive to at least one input signal basedat least partially from a measured TOC value of the inlet water; Whereinthe electronic ballast circuit controls the continuously variableintensity of the source of UV radiation to provide sufficient power tosaid source of UV radiation to remove a desired amount of TOC from fluidundergoing treatment while not producing more ultraviolet radiation thanis necessary to remove the desired amount of TOC; Removing at least aportion of any particulates from the water to produce the ultrapurewater; and Delivering at least a portion of the ultrapure water to thesemiconductor fabrication unit.
 11. The method of claim 10, furthercomprising regulating a rate of addition of the at least one precursorcompound based at least partially on the TOC value of the inlet water.